title: Responsiveness of urinary markers of bone resorption to orchiectomy and clodronate treatment in mature rats: a comparative study.
abstract: OBJECTIVE
  The aim of this study was to assess the responsiveness of two classes of bone resorption markers to the enhancement of osteoclastic activity induced by orchiectomy and to its inhibition by clodronate treatment in mature rats.
  
  
  METHODS
  Bone mineral density (BMD) at femural metaphysis, femural diaphysis, lumbar vertebrae, and the urinary excretion of pyridinoline (Pyr), deoxypyridinoline (D-Pyr), galactosylhydroxylysine (GHyl) and glucosylgalactosylhydroxylysine (GGHyl) were monitored at regular intervals for 30 days prior to and for 60 days following orchiectomy in eleven rats, divided into two groups: five rats untreated and the other six treated with clodronate.
  
  
  RESULTS
  Prior to orchiectomy, a significant (P < 0.01) decrease in BMD was observed only at the distal femural metaphysis. This decrease appeared to be associated with a time-dependent increase in the urinary excretion of all markers. Following orchiectomy, the BMD of the untreated group decreased significantly (P < 0.01) at all bone sites. The bone loss was accompanied by a significant (P < 0.01) increase in Pyr and D-Pyr concentrations in urine, whereas urinary GHyl and GGHyl did not change significantly. In the clodronate-treated group, the BMD of the three skeletal sites did not change significantly, while the urinary excretion of all urinary biochemical markers decreased significantly (P < 0.001).
  
  
  CONCLUSIONS
  This study showed that pyridinolines are able to monitor the bone response to orchiectomy and to clodronate treatment response in androgen-deficient mature male rat. whereas glycosides appear prone to confounding factors.
authors.affiliation: Unità Metabolica dell' Osso, Istituto Scientifico H San Raffaele, Milano, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Rubinacci
authors.forename: I
authors.initials: I
authors.lastname: Villa
authors.forename: V
authors.initials: V
authors.lastname: Sibilia
authors.forename: C
authors.initials: C
authors.lastname: Netti
authors.forename: G
authors.initials: G
authors.lastname: Moro
authors.forename: A
authors.initials: A
authors.lastname: Pecile
mesh_terms: D000375:Aging / Q000652:urine*; D000818:Animals; D015415:Biomarkers / Q000652:urine; D015519:Bone Density / Q000187:drug effects; D001862:Bone Resorption / Q000378:metabolism / Q000652:urine*; D004002:Clodronic Acid / Q000494:pharmacology*; D005269:Femur / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009919:Orchiectomy; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D015415:Biomarkers; D004002:Clodronic Acid